Taking images of a virus
Researchers from IBM's Almaden Research Centre and Stanford University have developed a new technique for seeing particles at the nanoscale using magnetic resonance imaging (MRI) techniques that are already widely used in hospitals.
They have combined ultrasensitive magnetic resonance force microscopy (MRFM) with 3D image reconstruction to achieve MRI with resolution under 10 nm. The image reconstruction converts measured magnetic force data into a 3D map of nuclear spin density, taking advantage of the unique characteristics of the “resonant slice” that is projected outward from a nanoscale magnetic tip. The basic principles are demonstrated by imaging the 1H spin density within individual tobacco mosaic virus particles sitting on a nanometer-thick layer of adsorbed hydrocarbons.
The result represents a 100 million-fold improvement in volume resolution over conventional MRI and demonstrates the potential of MRFM as a tool for 3D imaging on the nanometer scale.